A LARGE GROUP OF SUN-SPOTS.-Despite the fact that we are now drawing near to a sun-spot minimum, the solar disc has, during the past fortnight, exhibited an extensive group of spots. An observation on August 28 showed a bright patch of faculæ some distance south of the equator on the eastern limb, and on the following day a small spot was observed near the limb to the north of this. Observations on September 6 showed that there was a group of small spots in about the latitude of the previously observed faculæ, and this developed until, on September 11, it was a diamond-shaped group, of medium-sized spots, of which the longest diagonal was about one-sixth the length of the sun's diameter; each of the four main spots was surrounded by a number of smaller nuclei.

THE TRANSVAAL OBSERVATORY.-From a note in the Observatory (No. 413, p. 369) we learn that the Transvaal Government, on behalf of the Government observatory, has accepted the gift of a photographic astronomical telescope from Mr. Franklin Adams. The triple-objective is of 10 inches aperture, and made by Messrs. Cooke and Sons. Two guiding telescopes, each of 6 inches diameter, accompany the main instrument. The telescope is erected, and is to be employed mainly in assisting Prof. Kapteyn, in his studies of the construction of the sidereal universe, by securing photographs of the southern heavens.

ARTIFICIAL IMITATION OF LUNAR LANDSCAPE.-By cooling the slag from an iron-ore, smelted in a furnace and run off at a temperature of about 1100° C., Mr. Paul Fuchs succeeded in obtaining a surface structure which appears to be a very good imitation, in miniature, of a typical lunar landscape. The cooling was done with water applied in various ways, and produced craters, mountains, and plains according to the conditions of the slag and of the cooling. Photographs of the results are reproduced on plate accompanying No. 4348 of the Astronomische Nachrichten, wherein Mr. Fuchs describes his experiments.

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TEMPERATURE AND PRESSURE CONDITIONS IN THE SOLAR ATMOSPHERE. Two interesting letters dealing with the conditions obtaining in the solar atmospheres appear in No. 413 of the Observatory (September, pp. 359-63).

In the first, Mr. Buss returns to the question of the radial motions in sun-spots exhibited by Mr. Evershed's spectrograms, and shows how they may be interpreted to indicate that the visible umbral area of a spot is caused by the efflux of material from within rather than the influx of cooler matter. from above. The facts that spots often endure for months, and that Mr. Evershed finds that the radial motions are confined to the " reversing layer," i.e. to the lower levels of the sun's general atmosphere, are quoted as supporting this view; the vortices are effects of the outrush. This idea of the spots being produced by effluence leads to the sequel that the vapours of the actual spot must be at a higher temperature, whereas the observations of Sir Norman Lockyer and others show the reverse. To overcome this difficulty Mr. Buss suggests that the spectrum observed is that of the vapours high above the visual umbral level, and that, could we but observe the unveiled spectrum of the umbra itself, we would find it to be a bright-line spectrum.

In the second letter Mr. Evershed continues the discussion with Prof. Whittaker regarding pressure in the reversing layer. After' quoting experimental evidence to show that pressure-shifts are apparently independent of the manner in which luminosity is produced, Mr. Evershed points to the fact that the spectrum of the reversing layer consists of bright lines, as demonstrating that there is no enormous pressure on the emitting vapours; otherwise one would expect a more continuous spectrum. Finally, he states that measures of spot spectra, made at Kodaikanal, do exhibit small, differential pressure-shifts; the most affected lines are slightly displaced, relatively, towards the violet, thus indicating a umbræ of about one-third of an atmosphere less than in pressure in the the surrounding regions. Further details of these results are to be published shortly.

PARALLAX OF THE DOUBLE STAR 2398.-In No. 4348 of the Astronomische Nachrichten (p. 63), Dr. Karl Bohlin announces that the reduction of photographic observations, made at the Stockholm Observatory during 1907-8, shows

that the parallax of the double star 2398 is 0-484". This star thus becomes the nearest known neighbour, in the northern sky, to the solar system, its distance being 426,000 astronomical units, or 6-7 light-years. A previous observation by Lamp, at Kiel in 1883-7, gave the parallax as 0.353".

OUR FOOD FROM THE WATERS.1

AT the last meeting of the British Association in Canada (Toronto, 1897) I was able to lay before Section D a preliminary account of the results of running sea-water through four silk tow-nets of different degrees of fineness continuously day and night during the voyage from Liverpool to Quebec. During the eight days' traverse of the North Atlantic, the nets were emptied and the contents examined morning and evening, so that each such gathering was approximately a twelve-hours' catch, and each. day and each night of the voyage was represented by four gatherings. This method of collecting samples of the surface fauna of the sea in any required quantity per day or hour from an ocean liner going at full speed was suggested to me by Sir John Murray of the Challenger Expedition, and was first practised, I believe, by Murray himself in crossing the Atlantic. I have since been able to make similar traverses of several of the great oceans, in addition to the North Atlantic, namely, twice across the equator and through the South Atlantic, between England and South Africa, and four times through the Mediterranean, the Red Sea, and the Indian Ocean to Ceylon; and no doubt other naturalists have done much the same. The method is simple, effective, and inexpensive; and the gatherings, if taken continuously, give a series of samples amounting to a section through the surface layer of the sea, a certain volume of water being pumped in continuously through the bottom of the ship, and strained through the fine silk nets, the mesh of which may be one two-hundredth of an inch across, before passing out into the sea again. In examining with a microscope such a series of gatherings across an ocean, two facts are brought prominently before the mind: (1) the constant presence of a certain amount of minute living things; (2) the very great variation in the quantity and in the nature of these organisms.

Such gatherings taken continuously from an ocean liner give, however, information only in regard to the surface fauna and flora of the sea, including many organisms of fundamental importance to man as the immediate or the ultimate food of fishes and whales and other useful animals.

It was therefore a great advance in planktology when Prof. Victor Hensen (1887) introduced his vertical, quantitative nets, which could be lowered down and drawn up through any required zones of the water. The highly original ideas and the ingenious methods of Hensen and his colleagues of the Kiel School of Planktology-whether all the conclusions which have been drawn from their results be accepted or not-have at the least inaugurated a new epoch in such oceanographic work, and have inspired a large number of disciples, critics, and workers in most civilised countries, with the result that the distribution of minute organisms in the oceans and the fresh waters of the globe is now much more fully known than was the case twenty, or even ten, years ago. But perhaps the dominant feeling on the part of those engaged in this work is that, notwithstanding all this activity in research and the mass of published literature which it has given rise to, much still remains to be done, and that the planktologist is still face to face with some of the most important unsolved problems of biology.

It is only possible in an address such as this to select a few points for demonstration and for criticism-the latter not with any intention of disparaging the stimulating work that has been done, but rather with the view of emphasising the difficulties, of deprecating premature conclusions, and of advocating more minute and more constant observations.

The fundamental ideas of Hensen were that the plankton, or assemblage of more or less minute drifting 1 Evening discourse delivered before the British Association at Winnipeg on August 31 by Prof. W. A. Herdman, F.R.S.

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organisms (both animals and plants) in the sea, is uniformly distributed over an area where the physical conditions are approximately the same, and that by taking a comparatively small number of samples it would be possible to calculate the quantity of plankton contained at the time of observation in a given sea area, and to trace the changes of this plankton both in space and time. This was sufficiently grand conception, and it has been of great service to science by stimulating many workers to further research. In order to obtain answers to the problems before him, Hensen devised nets of the finest silk of about 6000 meshes in the square centimetre, to be hauled up from the bottom to the surface, and having their constants determined so that it is known what volume of water passes through the net under certain conditions, and yields a certain quantity of plankton.

Now if this constancy of distribution postulated by Hensen could be relied upon over considerable areas of the sea, far-reaching conclusions, having important bearings upon fisheries questions, might be arrived at; and such have, in fact, been put forward by the Kiel planktologists and their followers-such as the calculation by Hensen and Apstein that the North Sea in the spring of 1895 contained at least 157 billions of the eggs and larvæ of certain edible fish; and from this figure and the average numbers of eggs produced by the fish, their further computation of the total number of the mature fish population which produced the eggs-a grand conclusion, but one based upon only 158 samples, taken in the proportion of one square metre sampled for each 3,465,968 square metres of sea. Or, again, Hensen's estimation, from 120 samples, of the number of certain kinds of fish eggs in a part of the West Baltic, from which, by comparing with the number such eggs that would normally be produced by the fish captured in that area, he arrived at the conclusion that the fisherman catches about one-fourth of the total fish population-possibly a correct approximation, though differing considerably from estimates that have been made for the North Sea.

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Such generalisations are most attractive, and if it can be established that they are based upon sufficiently trustworthy data, their practical utility to man in connection with sea-fishery legislation may be very great. But the comparatively small number of the samples, and the observed irregularity in the distribution of the plankton (containing, for example, the fish eggs) over wide areas, such as the North Sea, leave the impression that further observations are required before such conclusions can be accepted as established.

Of the criticisms that have appeared in Germany, in the United States and elsewhere, the two most fundamental are (1) that the samples are inadequate; and (2) that there is no such constancy and regularity in distribution as Hensen and some others have supposed. It has been shown by Kofoid, by Lohmann, and by others that there are imperfections in the methods which were not at first realised, and that in some circumstances anything from 50 to 98 per cent. of the more minute organisms of the plankton may escape capture by the finest silk quantitative nets. The mesh of the silk is 1/200th inch across, but many of the organisms are only 1/3000th inch in diameter, and so car can readily escape.

Other methods have been devised to supplement the Hensen nets, such as the filtering of water pumped up through hose-pipes let down to known depths, and also the microscopic examination in the laboratory of the centrifuged contents of comparatively small samples of water obtained by means of closing water-bottles from various zones in the ocean. But even if deficiencies in the nets be thus made good by supplementary methods, and be allowed for in the calculations, there still remains the second and more fundamental source of error, namely, unequal distribution of the organisms in the water; and in regard to this a large amount of evidence has now been accumulated, since the time when Darwin, during the voyage of the Beagle on March 18, 1832, noticed off the coast of South America vast tracts of water discoloured by the minute floating alga Trichodesmium erythraeum. which is said to have given its name to the Red Sea, and which Captain Cook's sailors in the previous century 1 It is probable that too high a figure was taken for this.

called sea-sawdust." Many other naturalists since have seen the same phenomenon, caused both by this and by other organisms. It must be of common occurrence, and is widespread in the oceans, and it will be admitted that a quantitative net hauled vertically through such a trichodesmium bank would give entirely different results from a haul taken, it might be, only a mile or two away, in water under, so far as can be determined, the same physical conditions, but free from Trichodesmium.

It is

Nine nations bordering the north-west seas of Europe, some seven or eight years ago, engaged in a joint scheme of biological and hydrographical investigation, mainly in the North Sea, with the declared object of throwing light upon fundamental facts bearing on the economic problems of the fisheries. One important part of their programme was to test the quantity, distribution, and variation of the plankton by means of periodic observations undertaken four times in the year (February, May, August, and November) at certain fixed points in the sea. Many biologists considered that these periods were too few and the chosen stations too far apart to give trustworthy results. possible that even the original promoters of the scheme would now share that view, and the opinion has recently been published by the American planktologist, C. A. Kofoid-than whom no one is better entitled, from his own detailed and exact work, to express an authoritative verdict that certain recent observations can but reveal the futility of the plankton programme of the International Commission for the investigation of the sea. The quarterly examinations of this programme will, doubtless, yield some facts of value, but they are truly inadequate to give any trustworthy view of the amount and course of plankton production in the sea. That is the latest pronouncement on the subject, made by a neighbour of yours to the south, who has probably devoted more time and care to detailed plankton studies than anyone else on this continent.

It is evident that before we can base far-reaching generalisations upon our plankton samples, a minute study of the distribution of life in both marine and fresh waters at very frequent intervals throughout the year should be undertaken. Kofoid has made such a minute study of the lakes and streams of Illinois, and similar intensive work is now being carried out at several localities in Europe.

Too little attention has been paid in the past to the distribution of many animals in swarms, some parts of the sea being crowded and neighbouring parts being destitute of such forms, and this not merely round coasts and in the narrow seas, but also in the open ocean. For example, some species of Copepoda and other small crustacea occur notably in dense crowds, and are not universally distributed. This is true also of some of the diatoms, and also of larger organisms. Many naturalists have remarked upon the banks of Trichodesmium, of Medusa and Siphonophora, of Salpæ, of Pteropods. of Peridinians, and of other common constituents of the plankton. Cleve's classification into Tricho-Plankton (Arctic), Styli-Plankton (temperate), and Desmo-Plankton (tropical) depends upon the existence of such vast swarms of particular organisms in masses of water coming into the North Atlantic from different sources.

It is possible that in some parts of the ocean, far from land, the plankton may be distributed with the uniformity supposed by Hensen. It is important to recognise that at least three classes of locality exist in the sea in relation to distribution of plankton :

(1) There are estuaries and coastal waters where there are usually strong tidal and other local currents, with rapid changes of conditions, and where the plankton is largely influenced by its proximity to land.

(2) There are considerable sea areas, such as the centre of the North Sea and the centre of the Irish Sea, where the plankton is removed from coastal conditions, but is influenced by various factors which cause great irregularity in its distribution. These are the localities of the greatest economic importance to man, and to which attention should especially be directed.

(3) There are large oceanic areas in which there may

1 "Internationale Revue der H ydrobiologie und Hydrographie," vol. i. p. 846. December, 1908.

2 See Dakin, Trans. Biol. Soc. Liverpool, xxii, p. 544.

be uniformity of conditions, but it ought to be recognised that such regions are not those in which the plankton is of most importance to men. The great fisheries of the world, such as those of the North Sea, the cod fishery in Norway, and those on the Newfoundland Banks, are not in mid-ocean, but are in areas round the continents, where the plankton is irregular in its distribution.

As an example of a locality of the second type, showing seasonal, horizontal, and vertical differences in the distribution of the plankton, we may take the centre of the Irish Sea, off the south end of the Isle of Man. Here, as in other localities which have been investigated, the PhytoPlankton is found to increase greatly about the time of the vernal equinox, so as to cause a maximum, largely composed of Diatoms, at a period ranging from the end of March to some time in May-this year to May 28, in the Irish Sea. Towards the end of this period the eggs of most of the edible fishes are hatching as larvæ.

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This Diatom maximum is followed by an increase in the Copepoda (minute crustacea), which lasts for a considerable time during the early summer, and as the fish larvæ and the Copepoda increase there is a rapid falling off in Diatoms. Less marked maxima of both Diatoms and Copepoda may occur again about the time of the autumnal equinox. These two groups-the Diatoms and the Copepoda-are the most important economic stituents in the plankton. A few examples showing their importance to man may be given :-Man eats the oyster and the American clam, and these shell-fish feed upon Diatoms. Man feeds upon the cod, which in its turn may feed on the whiting, and that on the sprat, and the sprat on Copepoda, while the Copepoda feed upon Peridinians and Diatoms; or the cod may feed upon crabs, which in turn eat worms, ," and these feed upon smaller forms which are nourished by the Diatoms. Or, again, man eats the mackerel, which may feed upon young herring, and these upon Copepoda, and the Copepoda again upon Diatoms. All such chains of food matters from the sea seem to bring one through the Copepoda to the Diatoms, which may be regarded as the ultimate " producers of food in the ocean. Thus our living food from the waters of the globe may be said to be the Diatoms and other microscopic organisms as much as the fishes.

Two years ago, at the Leicester meeting of the British Association, I showed that if an intensive study of a small area be made, hauls being taken, not once a quarter or once a month, but at the rate of ten or twelve a day, abundant evidence will be obtained as to (1) variations in the distribution of the organisms, and (2) irregularities in the action of the nets. Great care is necessary in order to ensure that hauls intended for comparison are really comparable. Two years' additional work since in the same locality, off the south end of the Isle of Man, has only confirmed these results, viz. that the plankton is liable to be very unequally distributed over the depths, the localities, and the dates. One net may encounter a swarm of organisms which a neighbouring net escapes, and a sample taken on one day may be very different in quantity from a sample taken under the same conditions next day. If an observer were to take quarterly, or even monthly, samples of the plankton, he might obtain very different results according to the date of his visit. For example, on three successive weeks about the end of September he might find evidence for as many different far-reaching views as to the composition of the plankton in that part of the Irish Sea. Consequently, hauls taken many miles apart and repeated only at intervals of months can scarcely give any sure foundation for calculations as to the population of wide sea areas. It seems, from our present knowledge, that uniform hydrographic conditions do not determine a uniform distribution of plankton.

These conclusions need not lead us to be discouraged as to the ultimate success of scientific methods in solving world-wide plankton and fisheries problems, but they suggest that it might be wise to secure by detailed local work a firm foundation upon which to build, and to ascertain more accurately the representative value of our samples before we base conclusions upon them.

I do not doubt that in limited, circumscribed areas of water, in the case of organisms that reproduce with great

rapidity, the plankton becomes more uniformly distributed, and a comparatively small number of samples may then be fairly representative of the whole. That is probably more or less the case with fresh-water lakes, and I have noticed it in Port Erin Bay in the case of Diatoms. Ir spring, and again in autumn, when suitable weather occurs, as it did two years ago at the end of September, the Diatoms may increase enormously, and in such circumstances they seem to be very evenly spread over all parts and to pervade the water to some depth; but that is emphatically not the case with the Copepoda and other constituents of the plankton, and it was not the case even with the Diatoms during the succeeding year.

I have published elsewhere an observation that showed very definite limitation of a large swarm of crab Zoëas, so that none were present in one net while in another adjacent haul they multiplied several times the bulk of the catch and introduced a new animal in enormous numbers. Had two expeditions taken samples that evening at what might well be considered as the same station, but a few hundred yards apart, they might have arrived at very different conclusions as to the constitution of the plankton in that part of the ocean.

It is possible to obtain a great deal of interesting information in regard to the "hylokinesis" of the sea without attempting a numerical accuracy which is not yet attainable. The details of measurement of catches and of computations of organisms become useless, and the exact figures are non-significant, if the hauls from which they are derived are not really comparable with one another and the samples obtained are not adequately representative of nature. If the stations are so far apart and the dates are so distant that the samples represent little more than themselves, if the observations are liable to be affected by any incidental factor which does not apply to the entire area, then the results may be so erroneous as to be useless, or worse than useless, since they may lead to deceptive conclusions. It is obvious that we must make an intensive study of small areas before we draw conclusions in regard to relatively large regions, such as the North Sea or the Atlantic Ocean. Our plankton methods are not yet accurate enough to permit of conclusions being drawn as to the number of any species in the sea.

The factors causing the seasonal and other variations in the plankton already pointed out may be grouped under three heads, as follows:

(1) The sequence of the stages in the normal life-history of the different organisms.

(2) Irregularities introduced by the interactions of the different organisms.

(3) More or less periodic abnormalities in either time or abundance caused by the physical changes in the sea, which may be grouped together as weather.'

These are all obvious factors in the problem, and the constitution of the plankton from time to time throughout the year must be due to their interaction. The difficulty is to disengage them from one another, so as to determine the action of each separately.

Amongst the physical conditions coming under the third heading, the temperature of the sea is usually given a very prominent place. There is only time to allude here to one aspect of this matter.

It is often said that tropical and sub-tropical seas are relatively poor in plankton, while the colder Polar regions are rich. In fishing plankton continuously across the Atlantic it is easy from the collections alone to tell when the ship passes from the warmer Gulf Stream area into the colder Labrador current. This is the reverse of what we find on land, where luxuriant vegetation and abundance of animal life are characteristic of the tropics in contrast to the bare and comparatively lifeless condition of the Arctic regions. Brandt has made the ingenious suggestion that the explanation of this phenomenon is that the higher temperature in tropical seas favours the action of denitrifying bacteria, which therefore flourish to such an extent in tropical waters as seriously to diminish the supply of nitrogen food and so limit the production of plankton. Loeb, on the other hand, has recently revived the view of Murray, that the low temperature in Arctic waters so 1 "Darwin and Modern Science " (Cambridge, 1909), p. 247.

Considering the facts of photosynthesis, there is much to be said in favour of the view that the development, and possibly also the larger movements of the plankton, are influenced by the amount of sunlight, quite apart from any temperature effect.

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Bullen showed the correlation in 1903-7 between the mackerel catches in May and the amount of Copepod plankton in the same sea. The food of these Copepoda has been shown by Dakin to be largely Phyto-Plankton, and Allen has lately a correlated the average mackerel catch per boat in May with the hours of sunshine in the previous quarter of the year, thus establishing the following connection between the food of man and weather :-Mackerel-Copepoda-Diatoms-Sunshine. One more example of the influence of light may be given. Kofoid has shown that the plankton of the Illinois River has certain twenty-nine-day pulses, which are apparently related to the lunar phases, the plankton maxima lagging about six days behind the times of full moon. The light from the sun is said to be 618,000 times as bright as that from the full moon; but the amount of solar energy derived from the moon is sufficient, we are told, appreciably to affect photosynthesis in the Phyto-Plankton. The effectiveness of the moon in this photosynthesis to that of the sun is said to be as two to nine, and if that is so Kofoid is probably justified in his contention that at the time of full moon the additional light available has a marked effect upon the development of the Plankton.

Phyto

As on land, so in the sea, all animals ultimately depend upon plants for their food. The plants are the producers and the animals the consumers in nature, and the pastures of the sea, as Sir John Murray pointed out long ago, are no less real and no less necessary than those of the land. Most of the fish which man uses as food spawn in the sea at such a time that the young fry are hatched when the spring Diatoms abound, and the Phyto-Plankton is followed in summer by the Zoo-Plankton (such as Copepoda), upon which the rather larger but still immature food fishes subsist. Consequently, the cause of the great vernal maximum of Diatoms is one of the most practical of world problems, and many investigators have dealt with it in recent years. Murray first suggested that the meadows of the sea, like the meadows of the land, start to grow in spring simply as a result of the longer days and the notable increase in sunlight. Brandt has put forward the view that the quantity of Phyto-Plankton in a given layer of surface water is in direct relation to the quantity of nutritive matters dissolved in that layer. Thus the actual quantity present of the substance-carbon, nitrogen, silica, or whatever it may be-that is first used up determines the quantity of the Phyto-Plankton. Nathansohn in a recent paper contends that what Brandt supposes never really happens; that the Phyto-Plankton never exhausts any food constituent, and that it develops just such a rate of reproduction as will compensate for the destruction to which it is subjected. This destruction he holds is due to two causes: currents carrying the Diatoms to unfavourable zones or localities, and the animals of the plankton which feed on them. The quantity of Phyto-Plankton present in a sea will then depend upon the balancing of the two antagonistic processes-the reproduction of the Diatoms and their destruction. We still require to know their rate of reproduction and the amount of the destruction. It has been calculated that one of these minute forms, less than the head of a pin, dividing into two at its normal rate of five times in the day, would at the end of a month form a mass of living matter a million times as big as the sun. The destruction that keeps such a rate of reproduc1 M. B. A. Journ., viii.. 259. 2 Ibid., vii., 394.

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3 Monaco Bulletin, No. 145.

tion in check must be equally astonishing. It is claimed that the Valdivia results, and observations made since, show that the most abundant plankton is where the surface water is mixed with deeper layers by rising currents. Nathansohn, while finding that the hour of the day has no effect on his results, considers that the development of the Phyto-Plankton corresponds closely with evidence of vertical circulation. Like some other workers, he emphasises the necessity of continuous intensive work in one locality: such work might well be carried on both at some point on your great lakes and also on your Atlantic coast. The Challenger and other great exploring expeditions forty years ago opened up problems of oceanography, but such work from vessels passing rapidly from place to place could not solve our present problems-the future lies with the naturalists at biological stations working continuously in the same locality the year round.

The problems are most complex, and may vary in different localities-for example, there seem to be two kinds of Diatom maxima found by Nathansohn in the Mediterranean, one of Chatoceros due to the afflux of water from the coast, and one of Rhizosolenia calcaravis, due to a vertical circulation bringing up deeper layers of water. As a local example of the importance of the Diatoms in the plankton to man, let me remind you that they form the main food of your very estimable American clam. figures I now show, and some of the examples I am taking, are from the excellent work done on your own coasts in connection with fisheries and plankton by Prof. Edward Prince and Prof. Ramsay Wright and their fellow-workers at the Canadian biological station, on your eastern seaboard.

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The same principles and series of facts could be illustrated from the inland waters. Your great lakes periodically show plankton maxima, which must be of vast importance in nourishing animals and eventually the fishes used by man. Your geologists have shown that Manitoba was in post-Glacial times occupied by the vast lake Agassiz, with an estimated area of 110,000 square miles; and while the sediments of the extinct lake form your celebrated wheat fields, supplying food to the nations, the shrunken remains of the water still yield, it is said, the greatest fresh-water fisheries in the world. See to it that nothing is done to reduce further this valuable source of food! Quoting from your neighbours to the south, we find that the Illinois fisheries yield at the rate of a pound a day throughout the year of cheap and desirable food to about 80,000 people-equivalent to one meal of fish a day for a quarter of a million people.

Your excellent "whitefish" alone has yielded, I see, in recent years more than 5,000,000 lb. in a year; and all scientific men who have considered fishery questions will note with approval that all your fishing operations are now carried on under regulations of the Dominion Government, and that fish hatcheries have been established on several of your great lakes, which will, along with the necessary restrictions, form, it may be hoped, an effective safeguard against depletion. Much still remains to be done, however, in the way of detailed investigation and scientific exploitation. The German institutes for pond-culture show what can be done by scientific methods to increase the supply of food-fishes from fresh waters. It has been shown in European seas that the mass of living food matters produced from the uncultivated water may equal that yielded by cultivated land. When aquiculture is as scientific as agriculture, your regulated and cultivated waters, both inland and marine, may prove to be more productive even than the great wheat lands of Manitoba.

Inland waters may be put to many uses: sometimes they are utilised as sewage outlets for great cities, sometimes they are converted into commercial highways, or they may become restricted because of the reclamation of fertile bottom lands. All these may be good and necessary developments, or any one of them may be obviously best in the circumstances; but, in promoting any such schemes, due regard should always be paid to the importance and promise of natural waters as a perpetual source of cheap and healthful food for the people of the country.

UNIVERSITY AND EDUCATIONAL INTELLIGENCE.

A NUMBER of resolutions concerned with education were adopted last week at the Trade Union Congress held at Ipswich. Some called for the State maintenance of school children, for scientific physical education, and the development of the medical department of the Board of Education. Others demanded that secondary and technical education be an integral part of every child's education, and be secured by such a reform and extension of the scholarship system as would place a maintenance scholarship within the reach of every child, and thus make it possible for all children to be full-time day pupils up to the age of sixteen; and that the best intellectual and technical training be provided for the teachers of the children, that each educational district be required to train the number of pupil teachers demanded by local needs and to establish training colleges, preferably in connection with universities or university colleges. The interest in education thus manifested by the leaders of our working men may be regarded as a gratifying sign of the times. All who desire the welfare of the nation, would welcome any real improvement in our system of educating suitably the men upon whom the success of our industries largely depends; but many competent persons will doubt the wisdom of the great extension of our scholarship system demanded by the Trade Union Congress. In any system of awarding scholarships every care must be taken to ensure that each scholarship holder has shown by his previous record that he is mentally qualified to benefit by the secondary and technical education which the scholarship makes possible, and will complete the course at the school. It is important to educate every person to the full extent of his capabilities, but it is folly to imagine that every boy or girl who is made to attend a technical school must of necessity be able to benefit from such attendance.

THE technical colleges throughout the country are now issuing their programmes of work for the coming session. We have received the educational announcements of the Northampton Polytechnic Institute, Clerkenwell, the syllabus of classes at the Sir John Cass Technical Institute, Aldgate, London, and the prospectus of the East Ham Technical College evening classes. The educational aim of the Northampton Institute is to provide classes in technological and trade subjects, attention being first paid to the immediate requirements of Clerkenwell, the district of London in which the institute stands. The day courses are for students willing to give the whole of their time for one, two, or more years to a systematic training in technology. Day courses are provided in mechanical engineering, electrical engineering, watch-making, and horological engineering. In horology, a very large amount of time is given to workshop practice. There are also day courses in technical optics, electrochemistry, and other subjects. Evening classes are held in a very great variety of subjects. At the Aldgate institution graded courses of study extending over several years are provided in the various departments, and also special lectures, with accompanying laboratory practice, are given to meet the needs of persons holding responsible positions in the manufacturing establishments in the neighbourhood who desire to keep in touch with modern developments in applied science. Among the announcements of such special work may be mentioned the course on liquid, gaseous, and solid fuel arranged for the benefit of workers in chemical and engineering establishments and others concerned with the use of fuel as a motive power; that on the fermentation industries, with particular attention to microbiology; and that concerned with metallurgical problems. The evening classes at East Ham are under the general supervision of a responsible principal, and it is consequently possible for a student to obtain advice in the direction of securing a properly coordinated course of study continuing from year The numerous classes are adapted particularly to meet the requirements of young men and women engaged in the manual and other industrial trades of the locality.

to year.

SOCIETIES AND ACADEMIES.

PARIS.

Academy of Sciences, September 6.-M. Bouchard in the chair. The theoretical tides of the geoid, on the hypothesis of an absolute rigidity of the earth: Ch. Lallemand. Defining the geoïd as the surface of mean level confining a volume equal to that of the globe, the mean tides at the equator are worked out for both the solar and lunar waves.-The Brownian movement and molecular constants: Jean Perrin and M. Dabrowski. Experiments have been made on two emulsions of different substances containing minute particles in suspension. The results are applied to determine the constant N of Avogadro in Einstein's formula, and also in a formula based on the distribution of the particles under the action of gravity. The former leads to a value of 70 × 1022, and the latter to 70-5×10". The close accord of these results is a striking confirmation of the kinetic theory on which the formulæ are based. The most probable value of the charge of the electron from these values is 4.1X 10-19.-Calorimetric and cryoscopic constants of mercuric bromide: M. Guinchant The measured latent heat of fusion gives a cryoscopic corstant according to van 't Hoff's formula of 403; actual cryoscopic determinations in various solvents furnished a constant of 283 to 407, the average value being 340.-The life of fungi in fatty media: A. Roussy. For various moulds it was found that fatty substances were capable of replacing carbohydrates in culture media. The concentrations of fat most favourable for growth of the moulds were determined.-Some wild yams of Madagascar: Henri Jumelie and H. Perrier de la Bathie.-The experimental transmission of exanthematic typhus by the body louse: Charles Nicolle, C. Comte, and E. Conseil. The geological structure of the peninsula of Cape Bon, Tunis: A. Allemand-Martin.